JP4397526B2 - Honeycomb structure comprising an intermediate layer comprising at least one metal sheet - Google Patents

Description

[0001]
Field of the Invention
The present invention relates to a honeycomb body configuration having a housing in which a honeycomb body surrounded by an intermediate layer including a plurality of layer portions is disposed. Such an arrangement is used in particular for an automotive exhaust cleaning system, in particular for catalytic converters with a ceramic honeycomb body.
[0002]
BACKGROUND OF THE INVENTION
German Utility Model No. 80 19 813 already discloses a holder for a ceramic honeycomb body in which the honeycomb body is wrapped in a so-called swelling mat and arranged in a metal housing. The swollen mat can expand to fill cavities caused by different operating characteristics and manufacturing tolerances of the housing and honeycomb body, thereby ensuring a fixed support effect in long term operation. In general, the swelling mat includes mica pieces, and if there is a space around it, it absorbs moisture and expands. In order to stabilize such a swelling mat, the above-mentioned utility model proposes that a corrugated wire mat is integrated with the swelling mat. In order to prevent the swelling mat from being eroded at the end of the honeycomb body, a gas sealing ring is provided at the end of the honeycomb body so as to cover the gap filled with the swelling mat.
[0003]
Insulation between the housing and the honeycomb body when the honeycomb body in the exhaust system is heated to a temperature of 900 ° C. or higher during operation and components located in the vicinity of the honeycomb body configuration should be protected from this high heat It is also known to provide an intermediate layer.
[0004]
This thermal insulation layer may be an air layer, and since the heat conduction and thermal convection characteristics of air are low, this air layer insulates the housing from the high temperatures that occur in the honeycomb body during use of the honeycomb body configuration.
[0005]
It is known to provide an intermediate layer comprising a ceramic material instead of or in addition to the thermal insulation provided by the air layer. Again, the housing is insulated from the honeycomb body due to the low thermal conductivity and thermal convection properties of the ceramic material used. The above-mentioned swelling mat for holding the honeycomb body releases moisture at a very high ambient temperature, for example above 800 ° C., and thus contracts, so that the honeycomb body may become loose in the housing, Depending on the structure of the honeycomb body having a large load, it is necessary to insulate the swelling mat from the honeycomb body. For this purpose, it is already known that a honeycomb body is first provided with a heat insulating material and then sealed with a swelling mat for the first time.
[0006]
However, at a temperature higher than about 600 ° C., heat conduction occurs not only by heat conduction and heat convection but also by heat radiation, and the degree of heat radiation increases as the temperature increases. However, the above-described heat insulating materials and swelling mats known from the prior art provide only a small heat insulating effect.
[0007]
A further disadvantage of the known honeycomb body configuration is that the thermal insulation intermediate layer arranged between the housing and the honeycomb body is eroded by hot exhaust gas pulsating in the region of the end of the honeycomb body configuration. Even a ceramic intermediate layer, which itself has a very high wear resistance, is worn by the pulsating exhaust gas flow during operation, so that the insulation between the honeycomb body and the housing is disadvantageously impaired in the long-term operation of the honeycomb body configuration. It will be destroyed. For this reason, the honeycomb structure may be damaged, or even the entire honeycomb structure may be destroyed.
[0008]
SUMMARY OF THE INVENTION
In contrast to the above, an object of the present invention is to provide a honeycomb structure that reduces heat penetration due to heat radiation from the honeycomb body to the housing or the swelling mat, and preferably prevents or at least reduces the erosion of the intermediate layer. It is to be. Another object of the present invention is to provide a suitable sandwich structure that allows such a honeycomb structure to be easily manufactured.
[0009]
This object is achieved by the honeycomb structure according to claim 1 and the sandwich structure according to claim 11, respectively. Advantageous configurations and developments are described in the respective dependent claims.
[0010]
According to the invention, since the intermediate layer includes a plurality of layer portions including at least one metal foil or sheet, the heat flow from the honeycomb body to the housing by heat radiation is advantageously reduced. In addition, according to the present invention, since a plurality of layer portions including at least one ceramic material layer are provided, the honeycomb body configuration has good heat insulation characteristics in terms of heat conduction and heat convection. This is especially true when the thermal conductivity of the ceramic material is at a very low level.
[0011]
When at least one of the layer portions of the ceramic material is a swelling mat and closes the cavity in its vicinity by expanding when absorbing water, it is left between the housing and the honeycomb body during the manufacture of the honeycomb body configuration. Any cavity tee or cavity formed during operation is advantageously closed. This keeps the honeycomb body in a durable manner and firmly in place.
[0012]
Also, one embodiment of an intermediate layer which is advantageous from the point of view of the production procedure results from the fact that the honeycomb structure can be produced in a simple manner, in particular by winding or coiling, since the layer part is in the form of a metal sheet. In particular, when the sandwich structure is formed by joining the at least one metal sheet and at least one ceramic layer, the intermediate layer can be wound around the honeycomb body in a simple manner, and more specifically. Preferably, it may be wound at least once or a plurality of times when the requirement for heat insulation is high. The production of pre-shaped half shell parts in a sandwich structure is also a possible option.
[0013]
According to a further advantageous embodiment of the invention, the at least one metal sheet or foil at at least one end of the honeycomb body covers an adjacent ceramic layer at its end. This provides a particularly effective protection against the pulsating hot exhaust gas to be cleaned that flows into the honeycomb body configuration. This is because the exhaust gas no longer flows directly towards the ceramic layer, which prevents erosion of the ceramic layer.
[0014]
The metal sheet provided according to the invention and the ceramic layer that may be connected to it advantageously comprise structures, in particular corrugations that are corrugated wrinkles. This advantageously allows the metal sheet to be bent in the circumferential direction of the honeycomb body with a weak force.
[0015]
Additional features, advantages, and configurations of the invention are described below with reference to the drawings that are not to scale.
[0016]
[Detailed explanation]
With reference to FIG. 1 shown as a schematic partial cross-sectional perspective view that is not to scale, a honeycomb body configuration 1 according to the present invention is shown. The honeycomb body 3 has a passage 6, which is separated from each other by a partition wall 4 and a partition wall 5, in which a fluid from the internal combustion engine, preferably exhaust gas, flows in the flow direction S. Preferably, the honeycomb body comprises an extruded ceramic honeycomb body, in particular a body comprising a so-called thin wall ceramic. Both this type of ceramic honeycomb body and a honeycomb body made of a thin metal sheet must be firmly attached to the tubular casing 2 and further insulated from the tubular casing. In this embodiment, the mounting and thermal insulation described above is provided by an insulating layer portion 8 of ceramic material, a metal foil or sheet 9 and an additional layer portion 10 of ceramic material, preferably a swelling mat. These three layer parts together form an intermediate layer 7, which on the one hand holds the honeycomb body firmly in the tubular casing 2 while at the same time providing very good thermal insulation. The heat insulating layer portion 8 first prevents heat conduction and convection from the honeycomb body to the metal sheet 9. Further, since the metal sheet 9 acts as a radiation shield against heat radiation, the temperature of the layer portion 10 of the ceramic material is already considerably lower than that of the honeycomb body 3 itself in the operation of the honeycomb body configuration in the exhaust system of the automobile. For this reason, when the swelling mat is used as the layer portion 10 of the ceramic material, for example, a very large honeycomb body configuration, such as occurs in the case of an exhaust cleaning device, such as a catalytic converter arranged particularly near the outlet of an internal combustion engine. High operating temperatures are acceptable. It is pointed out that the housing 2 is generally 0.5 to 1 mm thick and the metal sheet 9 is preferably a very thin foil or sheet, in particular of a thickness of less than 50μ, preferably less than 30μ. Should be. The metal sheet 9 must in particular contain a material that is resistant to high temperature corrosion, in particular chromium and aluminum containing steel. The layer portions 8 and 10 of ceramic material are typically fiber mats, as is known in the prior art for supporting ceramic honeycomb bodies, which is a manufacturing tolerance for the housing 2 and the honeycomb body 3. Thickness required to compensate, and firmly support them in long-term operation. It should also be pointed out that a plurality of metal sheets and a plurality of layer portions which are continuous in the radial direction may be provided in order to improve the heat insulation against thermal radiation.
[0017]
FIG. 2 also shows a radial structure of a simple honeycomb body configuration according to the present invention, with part of a longitudinal section of the honeycomb body configuration. Continuously from the inside to the outside, the honeycomb body 3, the heat insulating layer portion 8 of the ceramic material, the metal sheet 9, the swelling mat 10 and the housing 2 are shown.
[0018]
FIG. 3 shows a preferred embodiment of the invention in the region of the end of the honeycomb body, with part of the longitudinal section of the honeycomb body configuration. As is known, ceramic materials, in particular fiber mats and swelling mats, etc. can be eroded by pulsating hot exhaust gases, so it is necessary to provide protection against this at one or preferably both ends of the honeycomb body construction according to the invention. is there. This can be achieved by a guard ring or step in the housing, as in the conventional configuration. However, according to the present invention there is another highly desirable solution, i.e. folding a metal sheet around an adjacent layer portion of the ceramic material as an end protection means. In the embodiment of FIG. 3, the metal sheet 11 is first wound around the honeycomb body 3, the ceramic layer portion 8 is arranged around it, then the metal sheet 9 is again arranged, and then a further layer of ceramic material. Place the portion 10. In this arrangement according to the invention, the end 12 and end 13 of the metal sheet 9 and metal sheet 11 are folded around the corresponding adjacent ceramic layer 8 and ceramic layer 10 respectively. Such a configuration can be manufactured in the simplest situation. First, a metal sheet 9 and a metal sheet 11 projecting at the end beyond the layer portion 8 and the layer portion 10 of the ceramic material are disposed around the honeycomb body 3. It can be produced by a procedure of winding and then folding the protruding end 12 and the protruding end 13 around the layer part 8 and the layer part 10 of ceramic material with a suitable tool. In this case, as shown in the embodiment of the present invention, the folding operation can be performed in such a manner that the end 12 and the end 13 of the metal sheet 9 and the metal sheet 11 are folded under the housing 2. . However, it is also possible to incorporate the end 12 and end 13 in the weld seam for joining the housing 2 to the adjacent exhaust system.
[0019]
It is particularly desirable for the production of a honeycomb body configuration according to the invention that the layer portions used as the intermediate layer 7 are previously produced as sandwich structures 17 and 27, respectively.
[0020]
One embodiment in this regard is shown in FIG. In this case, the heat insulating layer portion 8 of the ceramic material is disposed on one side of the metal sheet 9 by, for example, adhesion. A swelling mat is disposed on the other side of the metal sheet 9, and the end portion 14 of the metal sheet 9 is folded around the swelling mat 10. Such a configuration can be wound around the honeycomb body or it may already be pre-manufactured into a cylindrical or oval shape. When the heat insulating layer portion 8 includes a long ceramic fiber, it is sufficient to protect the swelling mat 10 with the folded end portion 14 of the metal sheet 9 because it is not significantly affected by the erosion by the pulsating exhaust gas.
[0021]
FIG. 5 shows a possible configuration of a sandwich structure with a metal sheet 9 folded at the end 15 in order to improve flexibility, for example when winding around a cylinder. The metal sheet 9 is a very thin sheet or foil, but the sandwich structure with the folded end formed therefrom is relatively stiff. To regain flexibility again, the entire sandwich structure may be made with a corrugated roll configuration, resulting in corrugation 18 shown in a highly exaggerated form in FIG. A very shallow extending corrugation is sufficient to provide flexibility. In this case, the folded end portion 15 of the metal sheet 9 is flattened at the end portion 16. Due to the sandwich structure 27 and the layer portion 8 of the ceramic material belonging to the swollen mat 10 arranged inside the metal sheet 9, the exhaust gas flows despite the small corrugation 18 of the sandwich structure 27. A possible passage is not formed outside the honeycomb body 3.
[0022]
The present invention is particularly suitable for a honeycomb body configuration for an exhaust catalytic converter in a region adjacent to an automobile engine. In this situation, the invention allows for a tight mounting of a metal or ceramic honeycomb body with a particularly thin wall, while at the same time providing good insulation of the honeycomb body to its housing. A preferred field of use is a honeycomb body configuration for a ceramic honeycomb body comprising a so-called thin wall ceramic with a wall thickness of less than 100 microns, preferably less than 50 microns.
[Brief description of the drawings]
FIG. 1 is a partial cross-sectional perspective view of one end portion of a first embodiment of the present invention.
FIG. 2 is a longitudinal sectional view of a part of the embodiment shown in FIG.
Fig. 3 is a longitudinal sectional view of a further embodiment in the region of one end of the honeycomb structure.
FIG. 4 is a partial cross-sectional perspective view of a sandwich structure according to the present invention.
FIG. 5 is a partial cross-sectional perspective view of a corrugated sandwich structure according to the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Honeycomb structure, 2 Housing, 3 Honeycomb body, 4,5 Partition, 6 Passage, 7 Intermediate layer, 8 Thermal insulation layer part of ceramic material, 9 Metal sheet, 10 Layer part of ceramic material, Swelling mat, 11 Metal sheet, 12, 14 Folded end of the metal sheet 9, 13 Folded end of the metal sheet 11, 15 Folded end of the metal sheet 9 in the corrugated sandwich structure 27, 16 Flat-crushed end of the sandwich structure 27 17, 27 Sandwich structure, 18 Corrugation, S Flow direction.

Claims (14)

A honeycomb body configuration (1) having a housing (2) in which a honeycomb body (3) surrounded by an intermediate layer (7) is disposed, the intermediate layer (7) comprising at least one metal sheet (9) ; look including the 10); a plurality of layer portions (8 formed from 10); 9 11) and at least one layer (8 ceramic material
At least one of the metal sheets (9; 11) includes an iron alloy containing chromium and aluminum, and has a thickness of less than 50 μm. At least one end of the honeycomb body (3) is a ceramic at the end. Shaped to contact and cover the surface of at least one adjacent layer (8) of material (12; 13; 14);
Furthermore, the at least one metal sheet (9; 11) is folded (12; 13; 14; 15) at the end around an adjacent layer (10; 8) of ceramic material , the honeycomb structure (1 ).   The honeycomb body configuration (1) according to claim 1, wherein the intermediate layer (7) comprises at least one layer portion of a metal sheet (9; 11) and at least two layer portions (8; 10) of a ceramic material. .   3. The swelling mat (10) according to claim 1 or 2, wherein the at least one layer portion (8; 10) of ceramic material is a swelling mat (10) that can close adjacent cavities by expanding when absorbing moisture. Honeycomb structure (1).   A honeycomb body configuration (1) according to any of the preceding claims, wherein at least one said layer portion (8) of ceramic material has a very low level of thermal conductivity.   A honeycomb body configuration (1) according to any of the preceding claims, wherein the layer portion (8; 10) of ceramic material is formed from at least one fiber mat. At least one metal sheet (9; 11) and at least one layer of ceramic material (8; 10) by bonding a sandwich structure; forming a (17 27), the sandwich (17; 27) is pre-Symbol honeycomb body The honeycomb body configuration (1) according to any one of claims 1 to 5, wherein the honeycomb body configuration (1) is wound around (3) in the circumferential direction at least once. The sandwich structure (17) is at least, the ceramic layer is a cross-heated material (8), a metal sheet; (9 11) and swelling mat (10), comprising in this order from the inner side to the outer side, in claim 6 The honeycomb structure (1) described. All metal sheets (9; 11) including the shaped areas (12; 13; 14; 15) and ceramic materials which can be joined to said metal sheets (9; 11) to form a sandwich structure (17; 27) Corrugation (17) is a structure (17) in which the metal sheet (9; 11) can be bent with a low level of force in the circumferential direction of the honeycomb body (3). The honeycomb structure (1) according to any one of claims 1 to 7 , wherein 18) is provided. 9. A honeycomb body structure (1) in particular according to any one of claims 1 to 8 , comprising a ceramic layer made of at least one metal sheet (9; 11) and a heat insulating fiber material (8) joined thereto. Sandwich structure for (17; 27). At least one metal sheet (9; 11), a ceramic layer (8) of insulating fiber material on one side of the metal sheet (9; 11), and on the other side of the metal sheet (9; 11). , and a layer (10) of fibrous material comprising Rise Jun materials, sandwich structure according to claim 9. 11. Sandwich structure according to claim 9 or 10 , comprising a plurality of metal sheets (9; 11) alternating with ceramic layers (8; 10). The sandwich structure according to any one of claims 9 to 11 , wherein the thickness of the metal sheet (9; 11) is less than 30µ. At least one of said metal sheet (9; 11), at least one adjacent ceramic layers; are folded around the (8 10) (12; 13; 14; 15), in any one of claims 9 12, The sandwich structure described. The sandwich structure is itself, the at easily wound is structure around the honeycomb body (3), and a passage which can pass through the exhaust gas outside aspect that is not made the form of the honeycomb body (3) 13. A sandwich structure according to any one of claims 9 to 12 having a structure.

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